Field of the Invention

The invention relates to fire-fighting equipment, more particular, to stationary and mobile fire extinguishing units wherein water containing foam-forming additives are used as a fire extinguishing substance.

Background of the Invention

The application of foam-forming additives in fire extinguishing compositions allows inflammable liquid fire sites to be effectively extinguished by cutting-off oxygen access to a burning surface. Also, the application of foaming agent enhances cooling of gas release zones of a fire site, inhibition of chemical oxidation reactions in the burning zone and reduction in the intensity of a radiant heat exchange.

Patent US 5445226 (IPC A62C 31/12, issued 29.08.1995) describes an apparatus for the generation of a fire extinguishing flow, comprising a lance including a flowing channel of axially symmetric shape, a branch pipe for feeding a liquid into the lance flowing channel, a nozzle located at an end part of the lance, and means for introducing a foaming solution into the flowing channel of the lance.

A flowing passage of the nozzle has a conical inlet portion diverging in the course of flow, an outlet portion of cylindrical shape, and a foaming chamber. Air ejection reach-through apertures are provided in the foaming chamber wall.

The means for introducing the foaming solution into the lance channel includes two inserts successively arranged within the flowing channel of the lance. The first insert is equipped with an inlet conical axial passageway converging in the course of flow of the liquid. An axial conical passageway of the second insert is diverging in the course of flow of the liquid. A liquid and foaming agent mixing chamber is disposed downstream of a plane of an outlet aperture of the first insert, the said chamber being defined by a cylindrical wall surface of the lance and a portion of the surface of the second insert.

The second insert is arranged in such a way as to define an annular gap between a plane of its inlet aperture and the plane of the outlet aperture of the first insert. A branch pipe for introducing the foaming solution communicates with the mixing chamber on the side of its lateral wall. The liquid supplied into the lance flows through the channel of the first conical insert and bypasses the gap to be further delivered into the channel of the second conical insert. A reduced pressure region is created within the mixing chamber in the vicinity of the gap. The

foaming agent is delivered into the mixing chamber through an annular gap between the inserts to form a thin film on the mixing chamber wall.

An ejection effect urges the foaming film to be delivered into the liquid stream. As a result, the liquid and the foaming agent are preliminarily mixed. The liquid and foaming agent 5 mixture is then directed into slits, which are equipped with sharp edges and are azimuthally offset with respect to one another. An intensive foaming occurs as the foaming solution flows through a channel system. The liquid and foaming mixture is then delivered into the foaming chamber where the foaming process is intensified due to mixing of the solution with an air flow ejected. l o The given apparatus is effective in the extinguishing of class "A" and class "B" fires, however, during operation of this apparatus the formation of a high- velocity foam-like jet is not ensured. The foam jet generated has a large cross sectional size and a relatively low velocity at the nozzle outlet. Also, it should be pointed out that the foaming process provided through the employment of a prior art apparatus is accompanied with the occurrence of

15 essential liquid stream energy losses for ejection of the foaming agent and the air flow. The above phenomena cause a decrease in a distance of discharging the fire extinguishing flow.

It is known from Patent US 2761516 (issued 04.09.1956) an apparatus for the generation of a fire extinguishing flow. This apparatus comprises a lance with a flowing channel of cylindrical shape and a branch pipe for feeding a liquid into the flowing channel of the lance.

20 A means for introducing a foaming solution into the lance flowing channel is made in the form of a central body-branch pipe coaxially arranged within the channel. A nozzle located on the lance end part includes a flowing passage composed of a conical inlet portion converging in the course of flow and a cylindrical outlet portion. The apparatus is further provided with an expansion chamber disposed between the foaming solution introduction means and the nozzle

25 inlet.

A foaming solution feeding branch pipe is formed as a converging nozzle with an outlet cylindrical portion oriented in the course of flow of the stream generated. Air ejection apertures are provided through the lance wall in the vicinity of the nozzle outlet port, said air ejection apertures being uniformly distributed along the perimeter of the flowing channel section.

30 After supplying of the liquid into the lance flowing channel, a reduced pressure region is created in the annular channel at the nozzle cut. This results in the ejection of air from the surrounding medium into the cavity of the flowing channel via apertures provided in the lance wall. An intensive mixing of the foaming solution stream with the air ejected results in the generation of an aerated-mechanical foam with large-sized bubbles. In the process of turbulent

flowing through the expansion chamber, the liquid stream is converted to a foam having small- sized bubbles. The foam-like stream produced in the expansion chamber is further delivered into the passage of the outlet nozzle of the lance, where a compact fire extinguishing flow is generated. The prior art apparatus allows aerated-mechanical foam flows to be generated, said flows being characterized by high stability. However, it should be noted that mixing of the fire extinguishing liquid with air leads to a significant decrease in a density of the fire extinguishing flow. Also, while passing through the expansion chamber, the foam-like stream is expanded and retarded due to the friction against the elongated flowing channel wall. Thus, the foam- like stream has a lower density and velocity as it approaches the outlet nozzle of the lance in comparison with said characteristics of the stream as it is near the cut of the foaming solution supply nozzle. The given factor predetermines reduction in the kinetic energy of the foam-like stream at the outlet of the lance nozzle. As a consequence, a distance of discharging the flow generated is decreased. The generation of the foam-like stream is also affected by dynamic fluctuations occurring during flowing of the stream through the lance flowing channel and through the channel of the expansion chamber.

The closest analog to the claimed invention is an apparatus for the generation of a fire extinguishing flow disclosed in Patent US 2478998 (issued 16.08.1949). The apparatus for the generation of a fire extinguishing flow comprises a lance with a flowing channel of axially- symmetric shape, a branch pipe for feeding a liquid into the lance flowing channel, a nozzle located at an end part of the lance, and a means for introducing a foaming solution into the lance flowing channel. A foam-like stream stabilizer as part of the apparatus is located within the lance flowing channel between the foaming solution introduction means and the nozzle inlet. An expansion chamber is provided within the lance flowing channel between the foaming solution introduction means and the mixed stream stabilizer. The flowing passage of the nozzle is composed of a conoid-shaped inlet portion converging in the course of flow and a cylindrical outlet portion.

A liquid and foaming agent supplying unit is positioned upstream from the inlet of the lance flowing channel. A central body of conical shape is located in the flowing channel of said unit, an apex of said body being oriented toward the liquid stream. An annular mixing chamber is provided between the inner surface of the case and the outer surface of the central body, said mixing chamber communicating with the foaming solution supply system through an annular gap provided in the outer wall of the flowing channel.

The liquid stream stabilizer is made in the form of two plates extending in parallel with the course of flow of the liquid and perpendicular to each other. A perforated conical partition is located within the channel of the expansion chamber, upstream from the liquid stream stabilizer. During operation of the apparatus, the liquid is supplied under pressure into the flowing channel of the lance. A reduced pressure region is created within the expansion chamber adjacent to the annular gap. Because of this, the foaming agent is ejected through the annular gap and mixed with the liquid stream. The fire extinguishing liquid stream is then delivered into the lance flowing channel where a mechanical foaming process is initiated due to mixing of the liquid with the air ejected from the ambient medium. The flow of foam-like fire extinguishing flow passes through the partition apertures to be further delivered into the liquid stream stabilizer and then into the passage of the outlet nozzle.

As the foam-like stream passes through the partition apertures, the flow velocity of the fire-extinguisher is reduced to thereby eliminate formation of swirls in the liquid stream and a liquid flow velocity profile is leveled across the section of the flowing aperture of the expansion chamber. In the converging portion of the nozzle passage, the velocity of the foam- like stream increases to the initial level (at the entrance to the expansion chamber). As a result of that a compact foam flow is generated at the nozzle outlet to be utilized as a fire extinguishing flow. It should be pointed out that in the prior art apparatus the stream turbulence is decreased in the zone upstream of the stream stabilizer owing to a reduction in the flow velocity of the foam-like stream within the expansion chamber. As a consequence, flowing of the liquid and foaming agent solution mixture through the expansion chamber of the apparatus is accompanied by essential losses in kinetic energy of the stream generated. The kinetic energy losses also occur in the process of ejecting the foaming solution into the mixing chamber and of ejecting air into the expansion chamber. The mechanical foaming process occurring in the lance flowing channel is also connected with essential energy losses.

It should be noted that in the apparatus described in Patent US 2478998 and also in other aforesaid prior art apparatuses, the foam-like flow is accelerated within the outlet nozzle of the apparatus, with the density of the foam-like stream being significantly lower than that of the liquid. Owing to the losses occurring, the velocity of the foam-like stream achieved at the outlet of the nozzle is substantially lower than the initial velocity of the liquid and the foaming solution, which are supplied into the flowing channel of the apparatus (into the mixing chamber).

Moreover, essential kinetic energy loses of the liquid stream caused by a non-uniform velocity profile of the generated liquid and foaming flow are characteristic of the apparatuses of the type under consideration. The given phenomenon is connected with dynamic disturbance occurring in the liquid stream, for example, during flowing thereof through turnings of a supply piping.

As a result of the above phenomena, the kinetic energy and pulsations of the generated foam-like flow downstream from the outlet nozzle cut are substantially lower than the values desirable for discharging a fire extinguishing flow to distances over 20 m.

Disclosure of the Invention

The object of the present invention is to provide an apparatus ensuring the generation of a high-velocity foam-like fire extinguishing flow, provided that the energy losses associated with the generation of such flow are minimal. A technical result achievable upon solution of the technical tasks set includes an increase in the fire extinguishing efficiency for extinguishing the fires of various classes (basically of "A" and "B" classes) by increasing the distance of discharging the fire extinguishing flow (over 20m) through reducing the energy losses for the generation of a high- velocity foam-like flow.

The given technical result is ensured by employment of an apparatus for the generation of a fire extinguishing flow, comprising a lance with a flowing channel of axially symmetric shape, a branch pipe for feeding a liquid into the flowing channel of the lance, and a nozzle located at an end part of the lance. The nozzle has a flowing passage comprising a conical or conoid-shaped inlet portion converging in the course of flow of the liquid, and an outlet portion of cylindrical shape. The apparatus also includes a foaming solution introduction means for introducing a foaming solution into the lance flowing channel. A mixed liquid and foaming stream stabilizer is disposed in the lance flowing channel, between the foaming solution introduction means and the nozzle inlet end. An expansion chamber is provided in the lance flowing channel between the foaming solution introduction means and the mixed stream stabilizer.

According to the present invention, a maximal diameter d _max and a minimal diameter d _m j _n of the inlet portion of the nozzle flowing passage, and also a length / _c of the outlet cylindrical portion of the nozzle flowing passage are selected on the following conditions:

2≤d _max /d _min <14 d _min =d _c ; / _o =(2÷10)d _c , where D _ec is a diameter of the expansion chamber within the lance flowing channel; d _c is a diameter of the outlet portion of the nozzle flowing passage.

The combination of the above essential features of the invention makes it possible to achieve the technical result by creating in the lance channel of the following zones sequentially arranged in the course of flow: the zone of mixing the working liquid with the foaming agent, the stream conversion zone where the stream parameters are leveled across the section of the flowing channel; the liquid stream acceleration zone for accelerating the liquid stream in a converging passage (converging tube) of the nozzle, and the foaming zone within the outlet cylindrical portion of the nozzle.

A significant increase in kinetic energy of the flow generated is reached through the employment of a liquid as a working fluid instead of a foam to be accelerated in the nozzle passage. A complete foaming process is provided at the cut of the outlet cylindrical portion of the nozzle.

Thus, because the liquid density is significantly higher than that of the foam, the stream density at the outlet of the acceleration zone is significantly higher in comparison with identical parameters of the foam-like flow. Also, the application of a liquid as a working fluid allows the flow velocity in the acceleration zone to be increased through the employment of a converging tube with a high convergence extent of a flow section of the nozzle flowing passage. It should be pointed out that converging nozzles with a low convergence extent of a section of a flowing passage: d _ma χ/d _m i _n ≤l-5, are commonly used in order to accelerate the foam. As an example, in the prior art apparatus (see US 2 478 998), a nozzle with a conical portion where a d _max /d _mm ratio is 1.3 is used. The given limitation is due to the fact that with an increase in the convergence extent of the section of the nozzle flowing passage, the continuity of foam feeding is disrupted and gaseous inclusions of large volume are created, with following deviation of the foam stream flow from a predetermined direction both within the nozzle passage and beyond the nozzle cut.

An essential condition providing a stable operation of the claimed apparatus and an achievement of the technical result is the fulfillment of the following condition: 2<d _max /d _min <14

The given condition characterizes, on the one hand, an increase in the velocity of the generated foam-like flow in comparison to the prior art apparatuses, where an intensive foam generation (2<d _ma χ/d _m j _n ) precedes the acceleration of the stream, and, on the other hand, a stable generation of a high- velocity stream of the desirable spatial homogeneity (d _max /d/ _min <14) is ensured.

It has been found from investigations that a stable generation of a high- velocity foam- like fire extinguisher flow with a distance of discharging exceeding 20m is provided with the fulfillment of the condition: 2<d _max /d _m j _n ≤14 for the used conical portion of the nozzle passage. Such a shape of the nozzle is applicable only for the acceleration of a liquid stream. It should be pointed out that the limitation on the maximal extent of convergence of the converging tube is connected with an essential increase in hydraulic losses and, consequently, with a reduction in the kinetic energy of the generated stream at the d _ma χ/d _m j _n ratio values exceeding 14. Also, in case a threshold value of the d _max /d _m j _n =14 is exceeded, the disruption in the continuity of the generated stream in the form of flow pulsations, the formation of a large volume of gaseous inclusions and the deviation of the jet from a predetermined direction of discharge of the fire-extinguisher onto a fire site are seen.

The benefits of the claimed apparatus are provided by the possibility of accelerating the working liquid to a maximal velocity before the liquid is converted to a foam. In this case, the generated high- velocity foam stream passes along the guiding walls of the nozzle cylindrical portion into a predetermined zone of a space without encountering any additional obstacles on the part of the components of the apparatus structure.

Another essential condition desirable for the achievement of a novel technical result is joining of the inlet aperture of the converging portion of the nozzle flowing passage with the outlet aperture of the expansion chamber channel and joining of an outlet aperture of the converging portion of the nozzle passage with an inlet aperture of the cylindrical portion of the nozzle passage:

The above condition of connecting the expansion chamber of the apparatus, the converging portion of the nozzle flowing passage and the cylindrical portion of the nozzle makes it possible to reduce kinetic energy losses of the liquid stream flowing through the expansion chamber to the nozzle outlet aperture.

In addition to that, the above condition allows the liquid stream of the working liquid and foaming solution mixture to flow to the foaming zone (the nozzle cylindrical portion) without any additional hydraulic resistance on the part of the flowing channel of the apparatus. It is known that a mechanical foam formation is initiated by non-continuous transition sites of pipings, or projections, dividers and also rough portions on the surface of the pipings through which the mixed liquid and foam stream is pumped.

As a result of implementing the essential condition characterizing flowing of the fire extinguisher liquid stream via the flowing channel of the apparatus without an intensive foaming before it reaches the foaming zone, the possibility of gaining a maximal velocity of

the fire extinguisher flow at the outlet of the apparatus nozzle is provided in the claimed apparatus.

The third essential condition allowing the sizes of the nozzle flowing passage to be defined is a proportion characterizing the selection of a length of the cylindrical portion of the nozzle flowing passage depending on its diameter: / _c =(2÷10)d _c .

The length of the cylindrical portion of the nozzle flowing passage is selected so as to provide, on the one hand, an intensive foaming in the accelerated liquid stream, which is a mixture of the working liquid and the foam solution, due to the cavitational processes (/ _c >2d _c ), and, on the other hand, the hydraulic resistance forces created during flowing of the liquid stream through the cylindrical passage would not cause disruption in the continuity of the foam-like flow generated (/ ₀ ≤10d ₀ ).

It has been found from investigations that the hydraulic resistance does not substantially affect the parameters of the foam-like stream, including reduction in the distance of discharge and disruption of the foam-like stream continuity, provided that the length of the cylindrical portion does not exceed ten times its diameter.

The limitation of the maximal length of the nozzle passage cylindrical portion is also connected with the losses of kinetic energy for the friction against the surface of the nozzle passage wall.

A stable foaming in the accelerated liquid stream is observed when the length of the cylindrical portion of the passage is at least two times the diameter thereof. It is advisable to note that the liquid stream is converted to the foam stream in the intensive foaming zone of the claimed apparatus owning to the volumetric gas generation in the liquid flowing through the cylindrical portion of the nozzle passage at a high velocity (of up to 100m/s). As known, upon flowing of a high-velocity liquid stream through the cylindrical portion, the cavitational processes start to exhibit at distances exceeding one radius from the inlet aperture of the passage (see, for example, Patent RU 2184619 Cl, column 14).

The gas bubbles formed serve as mechanical foaming centers in the liquid stream. A cavitation occurs when a static pressure in the liquid flowing through the passage drops to a value approximating a saturated liquid vapor pressure. With regard to a time delay between the moment gas bubbles are produced in the liquid volume (the bubbles are produced during time interval of about 10 ^"4 -10 ^'5 s) and the moment an intensive foaming solution agitation is started as a result of gas saturation and movement of the gas bubbles in the liquid stream, the length of the cylindrical portion of the nozzle passage is selected to be at least two times the diameter of the passage.

In other words, a minimal threshold value I ₀ is dependent upon the time interval during which a reduced static pressure acts in the liquid stream with the result that gaseous phase nuclei are formed and cavitational bubbles are produced and grown to critical sizes at which the bubbles collapse and smaller gaseous inclusions are formed, or said bubbles merge with adjacent bubbles to form greater inclusions. During conversion of the cavitational bubbles, the latter move in the liquid stream and collapse. The given phenomena initiate a mechanical foaming process.

The above foaming process differentiates the claimed invention from the technical embodiment disclosed in Patent US 2 478 998, which is considered the closest analog to the invention. In the apparatus according to Patent US 2 478 998, the foaming process occurs due to the ejection of an air flow from the surrounding medium into the cavity of the expansion chamber channel, the ejection apertures being located between the mixing chamber and the inlet of the expansion chamber of the apparatus.

The claimed invention is characterized in that the foaming process is initiated within the outlet portion of the nozzle passage as a result of formation, conversion and mixing with water of the cavitational bubbles produced within the liquid stream as the latter flows through the outlet cylindrical portion of the nozzle passage.

It has been found from investigations that a stable foaming and a maximal distance of discharging the foam fire extinguishing flow are ensured by restricting the length of the outlet portion of the nozzle flowing passage depending on the diameter d _c of the outlet portion of the nozzle flowing passage in compliance with the following condition: / _c =(2÷10)d _c . The minimal threshold value / ₀ is connected with the necessity of keeping the liquid in the reduced pressure zone for a predetermined time interval sufficient for the occurrence of gaseous phase nuclei, formation of cavitational bubbles and growth thereof to critical sizes. The maximal threshold is connected with the occurrence of kinetic energy losses for the friction against the surface of outlet portion of the nozzle passage.

When concrete values / _c are to be selected within a range of (2÷10)d _c , the influence of properties of a foaming agent upon the foaming process time should be taken into account. When foaming agents providing high foaming rates are used, the / _c value interval may be narrower.

Another important condition for creating a long-distance foam fire extinguishing flow is the necessity of decreasing tangential and radial velocity components across the liquid stream section. The non-uniform velocity profile is mainly due to swirling of the liquid stream in the supply piping bends.

Flow dynamic disturbance are formed in the liquid stream owing to the deviation of the velocity components of the stream layers at the inlet of the expansion chamber of the apparatus. Apart from supply piping bends and branches, the dynamic disturbance sources are also formed by sudden changes in the cross sectional size of the flowing channel. Also, the turbulence zones may be created in the liquid stream in the process of mixing the liquid and foam streams.

In order to substantially reduce a swirl (tangential) velocity component of the liquid stream at the nozzle inlet (by 40÷50%), at least one directing element is symmetrically located in the expansion chamber of the apparatus. According to a preferred version of embodiment of the invention, at least four directing elements formed as plates profiled in the course of flow of the liquid and an axially symmetric directing element formed as a tube may be provided in the expansion chamber. The end parts of plate-shaped directing elements are facing an axis of symmetry of the expansion chamber and are connected with the outer surface of the axially symmetric tube-shaped directing element axially located in the expansion chamber.

The employment of the directing elements in the expansion chamber of the apparatus allows the non-uniformity of the velocity profile across the mixed liquid and foaming solution stream to be eliminated. The directing elements located in the expansion chamber serve as a liquid stream former ensuring creation at the inlet of the stabilizing channels of a liquid stream with a minimal swirling (i.e., with a minimal tangential velocity component of a stream).

The liquid stream preliminarily swirled in the supply piping bends is partly straightened in the channels defined between the plate-shaped directing elements. The axial part of the liquid stream where swirling zones may be formed is defined by an inner diameter of the axially symmetric tube-shaped directing element. Because of this, the turbulent swirls restricted in the degree by the diameter of the tube may not add substantial disturbance into the liquid stream formed.

Also, the employment of the axially symmetric directing element formed as a tube located in the expansion chamber prevents the liquid from radial overflowing from peripheral zones defined by the profiled directing plates to a central axial zone of the liquid stream formed.

In the preferred version of embodiment of the apparatus, an inner diameter D _t of the axially symmetric directing element formed as a tube (a directing tube) is selected on the condition that: 0.1D _ec < D _t < 0.4D _ec .

It is also advisable that optimal values of a length / _t of the axially symmetric directing element (a directing tube) should be selected on the condition that: I _t =l _p =(3-5)D _t , where / _p is a length of the directed elements formed as plates (profiled directed plates) in the course of flow of the liquid. The above optimal sizes of the axially symmetric directing element formed as a tube define the terms providing the most effective suppression of the swirls created in the liquid stream produced.

It should be noted that with a decrease in the inner diameter D _t of the directing tube below O.lD _ec , the friction losses are increased. On the other hand, when the condition D _t ≤ 0.4D _ec is fulfilled, the occurring swirl formations are essentially lower in the degree than the turbulent swirls which may occur within the flowing channel of the expansion chamber of the apparatus.

The optimal length of the axially symmetric directing element is selected depending upon the fact that with the length / _t less than 3D _t a residual swirling is seen while with the length / _t greater than 5D _t the friction losses are substantially increased.

Implementation of the above conditions ensures the generation of a mixed working liquid and foaming stream where the swirling motion energy does not exceed 2% of the energy of a directed fire extinguishing flow at the nozzle outlet.

The mixed stream stabilizer provided in the flowing channel of the lance between the foaming solution introduction means and the nozzle inlet may be formed as a cellular structure composed of a number of plates oriented in the course of flow. The given embodiment of the stabilizer structure provides for creation of optimal conditions for eliminating flow swirls tending to occur in the process of forming the mixed liquid and foaming stream. It should be noted that the formation of swirls in the liquid stream and non-uniform distribution of the velocity profile in the stream affect formation of a high- velocity spatially oriented foam fire extinguishing flow.

During flowing of the mixed liquid stream with a disordered direction of the velocity component and unregulated velocity in the spatial regions defined by the cellular structure cells, individual streams are formed, said streams flowing in a predetermined direction: parallel with an axis of symmetry of the flowing channel of the expansion chamber. At the same time, the stream velocity profile is partly leveled across section of the flowing channel owing to dividing the stream into individual streams in the isolated damping cavities of the cellular structure cells of the stabilizer.

For providing maximally effective leveling of the stream velocity profile and ordering the directions of flow of the liquid layers in a single stream, a longitudinal (axial) size / _st of the stabilizer is selected depending on a diameter D _st of the stabilizer within the following range of values: 1.4D _st < / _st < 2.8D _st . The fulfillment of the above condition ensures maximally full smoothing of the swirls (turbulences), tending to occur upon mixing of the liquid stream with the foaming agent, at minimal kinetic energy losses owing to the friction against the surface of the stabilizer plates.

In the preferred version of embodiment of the invention, the foaming solution introduction means for introducing the foaming solution into the flowing channel of the lance is formed as a central body located within the flowing channel of the lance upstream of the expansion chamber inlet. In order to increase the efficiency of mixing the working liquid with the foaming solution, the outlet passageway of the given means is oriented toward the course of flow of the liquid stream.

Such implementation of the foaming solution introduction means ensures formation of a homogeneous mixed liquid and foaming solution stream with a minimal consumption of energy.

For increasing the efficiency of mixing the foaming solution with the liquid stream, the foaming solution introduction means may be equipped with a stream swirl unit. A screw-type device may be employed as a swirl unit. Guiding longitudinal or helical grooves are provided on the surface of the outlet passageway of the foaming solution introduction means in order to provide for a desirable direction of flowing of the foaming solution relative to the countercurrent working liquid stream.

For protecting an operator and a vehicle from heat fluxes issued from a high-temperature fire site, the apparatus includes as part a set of liquid atomizers movable relative to the lance.

A liquid supply branch pipe for the set of liquid atomizers communicates with the flowing channel of the lance upstream of the section where the outlet aperture of the foaming solution introduction means is positioned.

Brief Description of Drawings

The invention is further explained by examples of specific embodiment of the apparatus for the generation of a fire extinguishing flow with references to the accompanying drawings.

The exemplifying drawings illustrate the following: Fig. 1 is a longitudinal sectional view of an apparatus with a local view of a set of liquid atomizers, in a 1 :5 scale;

Fig. 2 is a longitudinal sectional view of an apparatus including directing elements provided in an expansion chamber, in a 1:5 scale;

Fig. 3 is a cross sectional view in a A-A plane of an apparatus illustrated in Fig. 2, in a 1 :2 scale;

Fig. 4 is a cross sectional view in a B-B plane of an apparatus illustrated in Fig. 2, in a 1 :2 scale.

Preferred Example of Embodiment of the Invention In an example of embodiment of the invention under consideration, an apparatus for the generation of a fire extinguishing flow is supposed for mounting on a fire engine (not shown in drawings). Alternative versions of utilization of the apparatus are also possible, for example on board the fire fighting ship.

According to the example of embodiment of the invention shown in Fig 1 , an apparatus for the generation of a fire extinguisher comprises a lance 1 with a flowing channel 2 of cylindrical shape. The lance 1 includes a case 3 and tubular sections 4, 5 and 6 joined to the case by means of threaded connections. A flowing channel of the case 3 communicates with a water feeding branch pipe for feeding water from a reservoir mounted on a vehicle (not shown in the drawing). The liquid is delivered from the reservoir into the flowing channel 2 by means of a pumping supply system.

A nozzle 7 is located on an end part of the tubular section 6 of the lance 1 by means of a captive nut 8. The joint between the end part of the tubular section 6 and the nozzle 7 is sealed by means of a sealing ring 9. A flowing passage of the nozzle 7 is composed of a conical inlet portion 10 which is converging in the course of flow of the liquid stream and a cylindrical outlet portion 11.

In the given example of embodiment of the invention, a maximal diameter d _max and a minimal diameter d _m j _n of the inlet conical portion 10 comply with the condition that (i.e., within a range of from 2 to 14). A diameter d _c of the outlet portion 11 of the flowing passage of the nozzle 7 is equal to d _m j _n . A length / _c of the outlet cylindrical portion 11

of the flowing passage of the nozzle 7 complies with the condition that: / _c -4d ₀ (i.e., within a range of from 2d _c to 10d _c ).

A foaming solution introduction means for introducing a foaming solution into the flowing channel 2 of the lance 1 is made in the form of a central body 12 axially arranged within the channel. The central body 12 comprises a nozzle 13 with an outlet passageway 14 axially aligned with the flowing channel 2. The nozzle 13 is connected to a foaming solution feeding branch pipe 15. The outlet passageway 14 is oriented toward the course of water stream in the flowing channel 2.

In the example of embodiment under consideration, the surface of the outlet passageway 14 is formed hexagonal. The faces of the hexagonal outlet passageway 14 facilitate turbulization of the foaming solution stream downstream from the outlet aperture of the passageway.

The branch pipe 15 is located in a hermetically sealed relationship within an aperture provided through the wall of the case 3. The branch pipe 15 extends perpendicular to an axis of symmetry of the flowing channel 2 and communicates through the pumping supply system with a vessel containing a supply of the foaming solution. In the example under consideration, a foam former of the AFFF 3M type is used as a foaming agent.

A stabilizer 16 for a mixed liquid and foaming stream is arranged within the flowing channel 2 of the lance 1 between the foaming solution supply means and the inlet of the nozzle 7. In the example of embodiment of the clamed invention, the stabilizer 16 is comprised of six plates 17 which are oriented along the course of flow of the stream. The mutually perpendicular plates 17 are interconnected so as to form a cellular structure. Two groups of plates, each including three plates, are oriented perpendicular to each other along the flowing channel 2. The cellular structure is provided in the tubular section 5 and fixed between end parts of adjacent tubular sections 4 and 6.

In the example under consideration, a diameter D _st of the stabilizer 16, which is defined by a maximal size of the plates 17 in the cross section of the flowing channel, and a longitudinal size / _st of the stabilizer 16, which is equal to the longitudinal (axial) size of the plates 17, are correlated as / _st = 1.5D _st (within the range of optimal values of from 1.4D _st to

A cylindrical expansion chamber 18 is disposed within the flowing channel 2 of the lance 1, between the central body 12 and the mixed liquid and foaming solution stream stabilizer 16. A diameter D _ec of the expansion chamber 18 is equal to a maximal diameter d _max

of the inlet portion 10 of the flowing passage of the nozzle 7. A length l _ec of the expansion chamber 18 is selected to be equal to 3.6D _ec .

In the example of embodiment under consideration, the diameter D _st of the stabilizer 16 slightly exceeds the diameter D _ec of the expansion chamber 18, which is due to the employed version of attachment of the stabilizer 16 within the flowing channel 2. The stabilizer 16 is fixed by means of end protrusions on the tubular sections 4 and 6. However, alternate attachments for the stabilizer are also possible.

The apparatus also includes a set of liquid atomizers composed of three atomizers 19 with outlet slits 20. The atomizers 19 have a single feeding collector 21 connected to a liquid feeding branch pipe 22. A stop valve 23 mounted on the branch pipe 22 is adapted for connecting the collector 21 to the flowing channel 2. The branch pipe 22 is communicating with the flowing channel 2 of the lance 1 in the zone upstream from the section where the outlet aperture of the foaming solution introduction means is positioned.

The liquid feeding branch pipe 22 is equipped with a revolving unit 24 for revolving the set of liquid atomizers to provide for angular displacement of the branch pipe 22 in conjunction with the liquid atomizers 19 relative to the lance 1 (in Fig. 1 the direction of displacement is designated by arrows). The unit 24 comprises a control lever 25 rigidly connected to the branch pipe 22.

Figures 1 to 4 illustrate the position of the set of liquid atomizers wherein the outlet slits 20 of the liquid atomizers 19 are oriented at an angle of 90° with respect to the axis of symmetry of the flowing channel 2 of the lance 1.

According to the second example of embodiment of the invention illustrated in Fig. 2, an apparatus for the generation of fire extinguishing flow is additionally equipped with four directing elements located within the inlet portion of the expansion chamber 18, said elements being formed as plates 28 profiled in the course of flow of the liquid, and an axially symmetric directing element formed as a tube 29 axially arranged in the cavity of the expansion chamber.

According to the example of embodiment of the invention under consideration, helical guiding grooves are provided on the surface of the outlet passageway 14 for turbulization of the foaming solution stream to effectively mix it with water stream. For this purpose, a special stream swirl unit may be also provided in the outlet passageway 14 of the nozzle 13. Such a swirl unit may be formed as an insert with tangential channels.

The plates 28 are provided in the inlet portion of the expansion chamber 18. End parts of the profiled plates 28 facing the axis of symmetry of the expansion chamber are rigidly joined

to the outer surface of the axially symmetric directing element - tube 29. The plates 28 and the tube 29 are symmetrically arranged in the flowing channel of the expansion chamber 18.

The directing elements formed as the plates 28 and the directing element formed as the tube 29 are made as a single hollow structure defining an insert 30. The attachment and retaining of the directing elements in a predetermined position relative to the axis of symmetry of the expansion chamber 18 are provided by means of mounting surfaces of the insert 30. In the example of embodiment of the invention under consideration, an inner diameter D _t of the axially symmetric directing element formed as the tube 29 is selected to be equal to 0.3D _eo to comply with the condition: 0.1D _ec ≤ Dt<0.4D _eo , where D _ec is an inner diameter of the expansion chamber 18.

A length / _t of the tube 29 is equal to a length / _p of the plates 28 along the course of flow of the liquid and constitutes 3.5D _t to comply with the condition that: / _t =/p=(3÷5)D _t .

The hollow insert 30 and the directing elements formed as plates 28 associated therewith and rigidly connected to the axially symmetric element formed as the tube 29 are fixed in the expansion chamber by means of an annular projection 31 provided on the outer surface of the insert 30. Upon mounting of the insert 30, the projection 31 is held between the end parts of the case 3 and of the tubular section 4. The flowing channel of the insert 30 is converging in the course of flow of the mixed working liquid and foaming solution stream.

In the example of embodiment of the claimed invention, the apparatus also includes the set of liquid atomizers comprising three atomizers 19 with outlet slits 20 (see Fig. 3), the single collector 21 for the atomizers 19, which is joined to the liquid feeding branch pipe 22. The stop valve 23 is provided on the branch pipe 22. The atomizers 19 communicate through the collector 21 and the branch pipe 22 with the flowing channel 2 of the lance 1. The branch pipe

22 is connected to the flowing channel 2 in the zone upstream of the section where the outlet aperture of the foaming solution introduction means is arranged, said means being formed as the nozzle 13.

Functioning of the apparatus for the generation of a fire extinguishing flow implemented according to the first example of embodiment of the invention (Fig. 1), is provided in the following manner. The apparatus is mounted on a vehicle and transported to a fire site. An operator directs the nozzle 7 of the apparatus by means of a guidance mechanism to a fire site. When needed, an additional liquid curtain is created with the use of the set of liquid atomizers. Such a curtain is adapted for protecting the operator and the vehicle from thermal radiation of the high-temperature fire site.

Upon actuation of the pumping supply system, water is delivered under the pressure of 0.9 MPa from a reservoir into the flowing channel 2 of the lance 1. Simultaneously, a portion of water is delivered from the flowing channel 2, through the liquid feeding branch pipe 22, the open stop valve 23 and the collector 21 to the liquid atomizers 19. The set of liquid atomizers is moved by the operator to a predetermined position by means of the lever 25 of the revolving unit 24.

Water film streams are created in the outlet slits 20 of the atomizers 19 to be atomized in the surrounding space for creating the protective gas-and-droplet curtain.

The foaming solution is fed under a working pressure by means of the pumping supply system from a vessel through the branch pipe 15 for feeding the foaming agent into the outlet passageway 14 of the nozzle 13. As the foaming solution flows along the flat walls of the outlet passageway 14, a directed stream is created. Then, owing to breaking away of the stream from the edges of outlet passageway 14, the foaming solution is dispersed and the swirl flow is created in the countercurrent water stream. Upon introduction of the foaming solution swirl flow into the countercurrent water stream, the working liquid is intensively mixed with the foaming agent at minimal energy consumption. The generated fire extinguishing stream with a concentration of about 10% is further delivered into the expansion chamber 18.

As the liquid fire extinguishing stream flows through the expansion chamber 18, the velocity profile is partly leveled across the section of the stream. The mixed stream is delivered from the expansion chamber 18 into the stream stabilizer 16. While the stream flows through the spatially separated channels of the cellular structure of the stabilizer 16, which are defined between the plates 17, the dynamic fluctuations are smoothed and the stream turbulization zones, which have been created upon mixing of the working liquid stream with the foaming agent, are eliminated.

The employment in the apparatus of the stabilizer 16 with a longitudinal size / _st selected within a range of optimal values of from 1.4D _st to 2.8D _st allows swirls occurred in the stream of liquid supplied into the nozzle 7 to be eliminated. A significant decrease in turbulization of the mixed liquid stream is seen with the longitudinal size / _st of the stabilizer 16 of at least 1.4D _st . When the longitudinal size / _st of the stabilizer 16 exceeds 2.8D _st , the mixed liquid flow velocity is reduced due to an increase in the kinetic energy losses of the liquid for the friction in the channels of the cellular structure of the stabilizer 16.

The mixed stream is delivered from the stabilizer 16 to the inlet of the nozzle 7 via the flowing channel of the tubular section 6. The mixed stream is accelerated in the inlet conical

portion 10 of the nozzle 7 owing to a smooth narrowing of the section of the flowing passage of the nozzle 7.

When the mixed stream reaches the inlet of the outlet cylindrical portion 11 of the flowing passage of the nozzle 7, it has a maximal flow velocity and, accordingly, a minimal static pressure. As the mixed stream flows via the flowing passage of the cylindrical portion 11 of the nozzle 7, the static pressure in the liquid stream is further decreased. When the pressure drop reaches the value approximating the pressure of the saturated vapor of the mixed stream, conditions are created for the occurrence of cavitation in the liquid.

An intensive process of forming and growing of cavitational bubbles to critical sizes occurs in the flowing passage of the cylindrical portion 11 at a distance of from d _c /2 to 2d _c from the inlet thereof. A mechanical foaming process is initiated upon displacement and collapsing of the bubbles in the mixed liquid and foaming solution stream. The result is that a foam-like low-expansion fire extinguishing flow is generated at the outlet of the nozzle 7, said stream flowing at the velocity of 40 m/s. The distance of discharging the fire extinguishing flow is up to 100 m with the total liquid consumption of about 40 1/s.

Contrary to the known prior art apparatuses, the employment of the claimed apparatus ensures a sequential formation and acceleration of the mixed working liquid and foaming solution stream, after which a mechanical foaming of the mixed stream is provided through the use of a cavitational effect. A substantial increase in the distance of discharging a flow is obtained by creating the conditions favorable for acceleration of the mixed liquid stream before initiation of the foam formation.

The application of the inlet conical portion 10 of the flowing passage of the nozzle 7 with a maximal diameter d _max to minimal diameter d _m j _n ratio selected within a range of 2÷14 allows the foam-like fire extinguishing flow to be accelerated to maximal possible velocities. With the inlet conical portion 10 having a narrowing extent exceeding d _max /d _m j _n =14 ₅ an unstable issuing of the generated stream from the outlet cylindrical portion 11 and, as a consequence, a reduced distance of discharging the fire extinguishing flow are seen.

The apparatus for the generation of a fire extinguishing flow, within the expansion chamber of which are located the directing elements (Fig. 2), operates in a manner similar to that of the first example of embodiment of the invention.

Upon actuation of the pumping supply system, water is supplied from the reservoir under an excessive pressure of 0.9 MPa into the flowing channel 2 of the lance 1. Simultaneously, a portion of water is delivered from the flowing channel 2, through the liquid feeding branch pipe 22, the open stop valve 23 and the collector 21 to the atomizers 19. The set of liquid

atomizers is moved by the operator to a predetermined position by means of the lever 25 of the revolving unit 24.

Water film streams are formed in the outlet slits 20 of the atomizers 19 to be dispersed in the surrounding space for creating a protective gas-and-droplet curtain. The foaming solution is supplied by means of the pumping supply system under the working pressure from the vessel through the foaming solution feeding branch pipe 15 into the outlet passageway 14 of the nozzle 13. As the foaming solution flows within the outlet passageway 14 via the helical grooves, a swirl flow is formed, said flow being directed toward the working liquid stream flowing via the flowing channel 2 of the lance 1. Upon introduction of the swirl flow of the foaming solution into the water stream, the working liquid is intensively mixed with the foaming agent.

The generated fire extinguishing stream is further delivered into the expansion chamber 18 at the inlet of which are positioned the directing elements formed as plates 28 profiled in the course of flow of the liquid and the directing tube 29 rigidly joined with the latter. The plates 28 and the tube 29 ensure formation of the mixed working liquid and foam stream in the expansion chamber 18. As the mixed stream flows around the directing plates 28 and the directing tube 29, the non-uniform flow velocity profile is smoothed across the section of the stream owing to the elimination of dynamic fluctuations and swirls in the stream. As the liquid stream flows through the expansion chamber 18, the flow velocity profile is further smoothed across the section of the mixed stream.

The mixed stream is delivered from the expansion chamber 18 into the stabilizer 16. While flowing through the axial channels of the cellular structure of the stabilizer defined between the plates 17, the dynamic fluctuations and swirls occurred in the stream upstream of the inlet of the nozzle 7 are additionally smoothed. While passing through the inlet conical portion 10 of the flowing passage of the nozzle 7, the mixed stream is accelerated. The accelerated liquid stream is then delivered from the inlet portion 10 into the outlet cylindrical portion 11 where an intensive foaming is provided owing to the use of a cavitational effect.

A gaseous nuclei formation process is initiated in the mixed water and foam stream flowing through the cylindrical portion 11. Upon formation of cavitational bubbles, the latter grow to critical sizes and further collapse.

As a result of intensive displacement of the cavitational bubbles in the liquid stream and collapsing thereof, a mechanical foaming process is provided in the mixed stream. A foam-like low-expansion fire extinguisher flow is generated at the outlet of the nozzle 7.

It has been found from investigations that because of an increase in the narrowing extent of the nozzle converging tube to the value of d _max /d _m j _n =5 and positioning of the directing elements (the plates 28 and the tube 29) within the expansion chamber of the apparatus, an additional increase in the distance of discharging the foam-like fire extinguishing flow is reached.

The employment of the apparatus implemented according to the above examples of embodiment of the invention, allowed the distance of discharging the foam-like fire extinguishing flow to reach 130 m. The consumption of the liquid fire extinguishing flow was 120 1/s at a delivery pressure of 0.9 MPa. Contrary to the prior art apparatuses, the employment of the claimed apparatus allows the mixed working liquid and foaming solution stream to be sequentially formed and accelerated, after which a mechanical foaming of the mixed stream is provided through the application of the cavitational effect.

The claimed apparatus provides for essential increase in the pulsation and kinetic energy of the foam-like fire extinguishing flow in an axial direction. This results in an increased distance of discharging the foam-like fire extinguishing flow.

Industrial Application of the Apparatus

Application of the apparatus for the generation of a fire extinguishing flow, implemented according to the present invention, provides an increase in the efficiency of extinguishing high- temperature fire sites owing to the generation of a long-distance low-expansion foam-like fire extinguishing flow.

The invention may be widely employed in constructing of mobile fire extinguishing units designed for extinguishing the fires occurring in inflammable liquid storage tanks, and also the fires occurred in case of emergency blowouts of petroleum products.

The above examples of embodiment of the invention are preferable, however they do not cover any other possible versions of embodiment of the invention implemented within the scope of claims of the invention with the use of means and methods known to those skilled in the art.